The instant invention relates to electroforming processes and more particularly to a method of electroforming a gold jewelry article utilizing a plurality of different gold/silver electroforming baths.
Electroforming processes for forming jewelry articles have heretofore been known in the art. In this regard, the U.S. Pat. to Desthomas No. 5,108,552 and Lechtzin No. 4,343,684 represent the closest prior art to the subject invention of which the applicant is aware. The patent to Desthomas relates to an electroforming process wherein an electroformed shell is formed in a plurality of stages, however, only one electroforming bath is utilized. The Patent to Lechtzin relates to an electroforming process where an electroformed piece is formed in two stages utilizing two different plating solutions. The first or inner electroformed layer is formed as a non-precious metal layer, such as a copper layer, and the outer layer is formed as a relatively thick layer of a precious metal, i.e. gold, silver, etc. In this process, the final electroformed piece is annealed at an elevated temperature to relieve internal stresses in the metal, and then the annealed piece is immersed in an acid bath to remove the inner non-precious metal layer. While these known electroforming processes produce precious metal shells which are suitable for use in manufacturing costume jewelry articles, they have generally been found to be expensive, and they have been found to have high rejection rates due to irregular surface textures, and denting in the finished products thereby formed.
The instant invention provides a method of electroforming high quality gold jewelry articles utilizing a first gold/silver electroforming bath which is effective for depositing a relatively soft, ductile gold alloy, and a second gold/silver electroforming bath which is effective for depositing a hard, brittle gold alloy. Prior to the electroforming steps of the instant invention, the method includes the preliminary steps of forming a wax mandrel in a desired configuration, inserting a copper wire into the mandrel and applying a conductive lacquer onto the mandrel and copper wire. The instant electroforming method comprises the steps of alternately electroplating soft and hard gold alloy layers onto the mandrel to form a laminated gold shell. After the last layer has been electroformed, the wax mandrel is melted and removed from the gold shell thereby forming a hollow jewelry article. The gold shell is then polished and finished into a jewelry article, such as an earring or pendant. It has been found that the laminated soft and hard gold alloy layers cooperate to relieve internal stresses in the metal and form a very strong and resilient metal shell. It has further been found that since the laminated structure of the shell is stronger than a conventional electroformed shell, the thickness of the laminated gold shell can be reduced, and therefore the finished shell can be made less expensively than a conventional gold shell. It has still further been found that when the outer gold layer is polished it provides a highly reflective finish so that the hollow shell resembles a solid gold article.
Accordingly, it is an object of the instant invention to provide a method of electroforming gold jewelry articles.
It is another object of the invention to provide an effective method of electroforming an item of gold jewelry which is essentially free from internal stresses.
It is still another object to provide a method of electroforming gold jewelry articles having very thin, and strong outer shells.
It is yet another to provide a method of electroforming a hollow gold jewelry article having a highly reflective finish which resembles a solid gold jewelry article.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds.